Thinking, Fast and Slow

Speaking of Availability Cascades
“She’s raving about an innovation that has large benefits and no
costs. I suspect the affect heuristic.”
“This is an availability cascade: a nonevent that is inflated by the
media and the public until it fills our TV screens and becomes all
anyone is talking about.”

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Tom W’s Specialty
Have a look at a simple puzzle:
Tom W is a graduate student at the main university in your state.
Please rank the following nine fields of graduate specialization in
order of the likelihood that Tom W is now a student in each of
these fields. Use 1 for the most likely, 9 for the least likely.
business administration
computer science
engineering
humanities and education
law
medicine
library science
physical and life sciences
social science and social work
This question is easy, and you knew immediately that the relative size of
enrollment in the different fields is the key to a solution. So far as you know,
Tom W was picked at random from the graduate students at the university,
like a single marble drawn from an urn. To decide whether a marble is
more likely to be red or green, you need to know how many marbles of
each color there are in the urn. The proportion of marbles of a particular
kind is called a 
base rate. Similarly, the base rate of humanities and
education in this problem is the proportion of students of that field among
all the graduate students. In the absence of specific information about Tom
W, you will go by the base rates and guess that he is more likely to be
enrolled in humanities and education than in computer science or library
science, because there are more students overall in the humanities and
education than in the other two fields. Using base-rate information is the
obvious move when no other information is provided.
Next comes a task that has nothing to do with base rates.
The following is a personality sketch of Tom W written during
Tom’s senior year in high school by a psychologist, on the basis
of psychological tests of uncertain validity:

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Tom W is of high intelligence, although lacking in true creativity.
He has a need for order and clarity, and for neat and tidy systems
in which every detail finds its appropriate place. His writing is
rather dull and mechanical, occasionally enlivened by somewhat
corny puns and flashes of imagination of the sci-fi type. He has a
strong drive for competence. He seems to have little feel and little
sympathy for other people, and does not enjoy interacting with
others. Self-centered, he nonetheless has a deep moral sense.
Now please take a sheet of paper and rank the nine fields of
specialization listed below by how similar the description of Tom
W is to the typical graduate student in each of the following fields.
Use 1 for the most likely and 9 for the least likely.
You will get more out of the chapter if you give the task a quick try;
reading the report on Tom W is necessary to make your judgments about
the various graduate specialties.
This question too is straightforward. It requires you to retrieve, or
perhaps to construct, a stereotype of graduate students in the different
fields. When the experiment was first conducted, in the early 1970s, the
average ordering was as follows. Yours is probably not very different:
1. computer science
2. engineering
3. business administration
4. physical and life sciences
5. library science
6. law
7. medicine
8. humanities and education
9. social science and social work
You probably ranked computer science among the best fitting because of
hints of nerdiness (“corny puns”). In fact, the description of Tom W was
written to fit that stereotype. Another specialty that most people ranked
high is engineering (“neat and tidy systems”). You probably thought that
Tom W is not a good fit with your idea of social science and social work

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(“little feel and little sympathy for other people”). Professional stereotypes
appear to have changed little in the nearly forty years since I designed the
description of Tom W.
The task of ranking the nine careers is complex and certainly requires
the discipline and sequential organization of which only System 2 is
capable. However, the hints planted in the description (corny puns and
others) were intended to activate an association with a stereotype, an
automatic activity of System 1.
The instructions for this similarity task required a comparison of the
description of Tom W to the stereotypes of the various fields of
specialization. For the purposes of tv>
If you examine Tom W again, you will see that he is a good fit to
stereotypes of some small groups of students (computer scientists,
librarians, engineers) and a much poorer fit to the largest groups
(humanities and education, social science and social work). Indeed, the